Membrane protein

The thesis is structured as follows: In Chapter 1, the scientific literature is summarized within the scope of this study. Chapter 2 provides a comprehensive overview of the principles of the applied computational approaches in this study. Chapter 3 identifies the important residues of the LsIA/α7 nAChR complex that affect the interactions between the toxin and the membrane protein due to C-terminal carboxylation of LsIA. The effects of C-terminal modification of LsIA on interactions with α3β2 nAChR, involved in cardiovascular diseases, were also investigated in Chapter 4.

234p runthenight04 02-02-2023 11 3   Download

Regulator of G protein signaling (RGS) proteins are gatekeepers regulating the cellular responses induced by G protein-coupled receptor (GPCR)-mediated activation of heterotrimeric G proteins. Specifically, RGS proteins determine the magnitude and duration of GPCR signaling by acting as a GTPase-activating protein for Gα subunits, an activity facilitated by their semiconserved RGS domain. The R7 subfamily of RGS proteins is distinguished by two unique domains, DEP/DHEX and GGL, which mediate membrane targeting and stability of these proteins.

13p caothientrangnguyen 09-05-2020 27 1   Download

Despite high vaccination coverage after introduction of whole cell (wP) and acellular pertussis (aP) vaccines, pertussis resurgence has been reported in many countries.

9p nutifooddau 27-01-2019 18 2   Download

Aralar1 and citrin are members of the subfamily of calciumbinding mitochondrial carriers and correspond to two isoforms of the mitochondrial aspartate/glutamate carrier (AGC). These proteins are activated by Ca2+ acting on the external side of the inner mitochondrial membrane. Although it is known that aralar1 is expressed mainly in skeletal muscle, heart and brain, whereas citrin is present in liver, kidney and heart, the precise tissue distribution of the two proteins in embryonic and adult tissues is largely unknown....

8p system191 01-06-2013 36 4   Download

Human immunodeficiency virus type 1 protein R (HIV-1 Vpr) promotes nuclear entry of viral nucleic acids in nondividing cells, causes G2 cell cycle arrest and is involved in cellular differentiation and cell death. Vpr subcellular localization is as variable as its functions. It is known, that consistent with its role in nuclear transport, Vpr localizes to the nuclear envelope of human cells. Further, a reported ion channel activity of Vpr is clearly dependent on its localization in or at membranes.

6p system191 01-06-2013 36 4   Download

In a previous study, the S100A8/A9 protein, a Ca2+- and arachidonic acid-binding protein, abundant in neutrophil cytosol, was found to potentiate the activation of the redox component of the O2– generating oxidase in neutrophils, namely the membrane-bound flavocytochrome b, by the cytosolic phox proteins p67phox, p47phox and Rac ` (Doussiere J., Bouzidi F. and Vignais P.V. (2001) Biochem. Biophys. Res. Commun. 285, 1317–1320). This led us to check by immunoprecipitation and protein fractionation whether the cytosolic phox proteins could bind to S100A8/A9.

10p system191 01-06-2013 30 4   Download

The expression of mitochondrial and hydrogenosomal ADP/ATP carriers (AACs) from plants, rat and the anaerobic chytridiomycete fungus Neocallimastix spec. L2 in Escherichia coli allows a functional integration of the recombinant proteins into the bacterial cytoplasmic membrane. For AAC1 and AAC2 from rat, apparent Km values of about 40 lM for ADP, and 105 lM or 140 lM, respectively, for ATP have been determined, similar to the data reported for isolated rat mitochondria.

10p system191 01-06-2013 37 3   Download

The main component of cerebral amyloid angiopathy (CAA) in Alzheimer’s disease is the amyloid-b protein (Ab), a 4-kDa polypeptide derived from the b-amyloid protein precursor (APP). The accumulation of Ab in the basement membrane has been implicated in the degeneration of adjacent vascular smooth muscle cells (VSMC). However, the mechanism of Ab toxicity is still unclear. In this study, we examined the effect of substrate-bound Ab on VSMC in culture. The use of substrate-bound proteins in cell culture mimics presentation of the proteins to cells as if bound to the basement membrane.

9p system191 01-06-2013 43 5   Download

Laboratory for Lipoprotein Chemistry and 4Flanders Interuniversity Institute for Biotechnology, Department of Medical Protein Research, Faculty of Medicine, Department of Biochemistry, Ghent University, Belgium; 2Laboratory of Biomolecular Dynamics, Katholieke Universiteit Leuven, Belgium; 3Ecole Normale Supe´rieure, Paris, France Penetratin is a 16-amino-acid peptide, derived from the homeodomain of antennapedia, a Drosophila transcription factor, which can be used as a vector for the intracellular delivery of peptides or oligonucleotides....

9p system191 01-06-2013 33 4   Download

The present work reports isolation and characterization of a highly glycosylated protein from bovine milk fat globule membranes, known as PAS III. Partial amino-acid sequencing of the purified protein allowed construction of degenerate oligonucleotide primers, enabling isolation of a full-length cDNA encoding a protein of 330 amino-acid residues. N-terminal amino-acid sequencing of derived peptides and the purified protein confirmed 76% of the sequence and demonstrated presence of a cleavable signal peptide of 23 residues, leaving a mature protein of 307 amino acids.

9p system191 01-06-2013 50 4   Download

A series of thylakoid membrane proteins, including PsbX, PsbY and PsbW, are synthesized with cleavable signal peptides yet inserted using none of the known Sec/SRP/Tat/ Oxa1-type insertion machineries. Here, we show that, although superficially similar to Sec-type signal peptides, these thylakoidal signal peptides contain very different determinants.

11p system191 01-06-2013 46 4   Download

The amyloid protein precursor (APP) was incorporated into liposomes or phospholipid monolayers. APP insertion into liposomes required neutral lipids, such as L-a-phosphatidylcholine, in the target membrane. It was prevented in vesicles containing L-a-phosphatidylserine. The insertion was enhanced in acidic solutions, suggesting that it is modulated by specific charge/charge interactions. Surfaceactive properties and behaviour of APP were characterized during insertion of the protein in monomolecular films of L-a-phosphatidylcholine, L-a-phosphatidylethanolamine or L-a-phosphatidylserine. ...

9p research12 01-06-2013 42 4   Download

In avian species, an egg envelope homologous to the mammalian zona pellucida is called the perivitelline membrane. We have previously reported that one of its components, a glycoprotein homologous to mammalian ZPC, is synthesized in the granulosa cells of the quail ovary. In the present study, we investigated the proteolytic cleavage of the newly synthesized ZPC and the secretion of ZPC from the granulosa cells. Western blot analysis of the cell lysates demonstrated that the 43-kDa protein is the precursor of mature ZPC (proZPC), and is converted to the 35-kDa protein before secretion. ...

9p research12 01-06-2013 37 4   Download

A technique has been developed to search a proteome database for new members of a functional class of membrane protein. It takes advantage of the highly conserved secondary structure of functionally related membrane proteins. Such proteins typically have the same number of transmembrane domains located at similar relative positions in their polypeptide sequence. This gives rise to a characteristic pattern of peaks in their hydropathy profiles.

7p research12 01-06-2013 34 4   Download

Cytochrome P450foxy (P450foxy, CYP505) is a fused protein of cytochrome P450 (P450) and its reductase isolated from the fungus Fusarium oxysporum, which catalyzes the subterminal (x-1x-3) hydroxylation of fatty acids. Here, we produced, purified and characterized a fused recombinant protein (rP450foxy) using the Escherichia coli expression system. Purified rP450foxy was catalytically and spectrally indistinguishable from the native protein, but most of the rP450foxy was recovered in the soluble fraction of E. coli cells unlike the membrane-bound native protein....

8p research12 01-06-2013 58 4   Download

The ÔMediterraneanÕ variant of glucose-6-phosphate dehydrogenase (G6PD) deficiency is due to the C563CT point mutation, leading to replacement of Ser with Phe at position 188, resulting in acute haemolysis triggered by oxidants. Previous work has shown increased formation of altered aspartate residues in membrane proteins during cell ageing and in response to oxidative stress in normal erythrocytes. These abnormal residues are specifically recognized by the repair enzyme L-isoaspartate (D-aspartate) protein O-methyltransferase (PCMT; EC 2.1.1.77). ...

8p research12 01-06-2013 39 4   Download

MFG-E8 (milk fat globule-EGF factor 8) is a peripheral membrane glycoprotein, which is expressed abundantly in lactating mammary glands and is secreted in association with fat globules. This protein consists of two-repeated EGF-like domains, a mucin-like domain and two-repeated discoidinlike domains (C-domains), and contains an integrin-binding motif (RGD sequence) in the EGF-like domain. To clarify the role of each domain on the peripheral association with the cell membrane, several domain-deletion mutants of MFG-E8 were expressed in COS-7 cells. ...

10p research12 01-06-2013 54 3   Download

The CD53 antigen is a member of the tetraspanin membrane protein family that is expressed in the lymphoid-myeloid lineage. We have studied the implication of CD53 antigen in signal transduction by determining the effect of its ligation on the c-Jun N-terminal kinase (JNK) in different cell types. Ligation of the rat or human CD53 antigen induces a threeto fourfold transient activation of JNK activity that peaks at 3–5 min. The effect was detected by assaying the endogenous or exogenous (transfected) JNK activity....

10p research12 01-06-2013 44 6   Download

Casein kinases I (CKI) are serine/threonine protein kinases widely expressed in a range of eukaryotes including yeast, mammals and plants. They have been shown to play a role in diverse physiological events including membrane trafficking. CKIa is associated with synaptic vesicles and phosphorylates some synaptic vesicle associated proteins including SV2. In this report, we show that syntaxin-1A is phosphorylated in vitro by CKI on Thr21.

6p research12 01-06-2013 40 3   Download

Lipid rafts are liquid-ordered membrane microdomains with a unique protein and lipid composition found on the plasma membrane of most, if not all, mammalian cells. A large number of signalling molecules are concentrated within rafts, which have been proposed to function as signalling centres capable of facilitating efficient and specific signal transduction. This review summarizes current knowledge regarding the composition, structure, and dynamic nature of lipid rafts, as well as a number of different signalling path- ways that are compartmentalized within these microdomains....

16p research12 01-06-2013 38 3   Download